Stihl TS420 - Muffler bolts keep breaking

[tstation77]

Have a Stihl TS 420 cut off saw. Primarily use it for cutting metal decking and steel work. Have owned the saw for a couple years now and within the past two months I have had to replace the muffler bolts twice. The same bolt snaps inside the block and has to be removed using an easy out bit. Last time I tried to use hi temp lock tite and it happened again. Any advice on how to fix this issue? Has anyone else had this issue with Stihl equipment?

 

[miterman]

I own a masonry company and have around a dozen of these saws. Those bolts have broken off on nearly every one of them. These are great saws, but it is a fatal flaw and it never happened on any of our older 400's. I have no luck with easy outs, so I end up having to get replacement jugs. It stinks having to put a new cylinder on a saw that runs perfectly except for the deafening noise. Stihl gave me the replacement jugs for free on a few of them but they are not going to stand behind them any more so I am considering going with Husquavarna from now on.

 

[tool_king]

miterman
Husquavarna parts more money .More plastic parts on saw.

 

[Former Wrench]

The next time you replace with a new jug, try taking the bolt out and replacing it with a grade 8 or aircraft quality bolt and see if that gives you anymore life.

 

[Tinkerer]

Are you using a torque wrench when reinstalling the bolts ?

 

[fixou812]

You could install a new gasket using stainless steel bolts
tig or wire weld a piece of stainless welding rod....
a jumper between the two bolts so they can't back off.

 

[Nige]

Problem is that the OP's muffler bolts are breaking, not backing off - at least that's how I read it.
It may be that the bolt is over-stressed which would lead it to fail once it had been through a few dozen cold->hot->cold cycles. Is there any space available to use a slightly longer bolt with a spacer over the shank to take up the additional length..? That's the usual solution for exahust bolts breaking.

 

[lantraxco]

Yep, long as you can as Nige suggests, and if at all possible use studs and nuts, always works better for me, though I haven't used them on cut off saws, just motorcycles engines.